Articular surfaces
The hip joint consists of an articulation between the head of the femur and the socket of the pelvis.
The acetabulum is a cup-shaped depression located in the inferolateral part of the pelvis. Its cavity is deepened by the presence of a fibrocartilaginous collar, the acetabular labrum. The head of the femur is hemispherical, and fits completely into the concavity of the acetabulum.
Both the acetabulum and the head of the femur are covered with articular cartilage, which is thickest where weight-bearing.
The capsule of the hip joint attaches to the rim of the acetabulum proximally. Distinctly, it joins the intertrochanteric line anteriorly and the neck of the femur posteriorly.

Ligaments
The ligaments in the hip joint work to increase stability. They can be divided into two groups: intracapsular and extracapsular:
Intracapsular
The only intracapsular ligament is the ligament of the femoral head. It is a relatively small structure, which goes from the acetabular fossa to the fovea of the femur.
Extracapsular
There are three main extracapsular ligaments, continuous with the outer surface of the capsule of the hip joint:
- iliofemoral ligament - Pubofemoral
- Ischiofemoral

Irrigation
The medial circumflex femoral artery is responsible for most of the arterial supply (the lateral circumflex femoral artery has to penetrate through the thick iliofemoral ligament).

Innervation of the hip joint
The hip joint is innervated mainly by the sciatic, femoral, and obturator nerves. These same nerves innervate the knee, which explains why pain can be referred to the knee from the hip and vice versa.

Stabilization factors
The main function of the hip joint is to bear weight. There are a number of factors that act to increase joint stability.
There is a horseshoe-shaped fibrocartilaginous ring around the acetabulum that increases its depth, known as the acetabular labrum. The increase in depth provides a greater articular surface, further improving joint stability.

In addition, the muscles and ligaments work reciprocally in the hip joint.

Source: Topographic Anatomy. "Hip Joint". https://anatomiatopografica.com/areas-anatomicas/articulacion-de-la-cadera/. Accessed May 9, 2023."